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PubMedDate not supplied

Health effects of mechanical vibration.

In this study, the health disorders caused by occupational exposure to whole-body vibration (WBV) and hand-transmitted vibration (HTV) are reviewed. Long-term occupational exposure to intense WBV is associated with an increased risk for disorders of the lumbar spine and the connected nervous system. With a lower probability, the neck-shoulder, the gastrointestinal system, the female reproductive organs, the peripheral veins, and the cochleo-vestibular system are also assumed to be affected by WBV. However, there is a weak epidemiologic support for WBV-induced disorders of organ systems other than the lower back. Prolonged exposure to HTV from powered processes or tools is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and osteoarticular systems of the upper limbs. The complex of these disorders is called hand-arm vibration syndrome. This paper provides qualitative and quantitative information on occupational exposure to mechanical vibration in the European Union based on a report by the European Agency for Safety and Health at Work (2000). Protection and health surveillance of vibration-exposed workers are discussed in the context of the European Directive 2002/44/EC on mechanical vibration and the guidelines prepared by the Italian Society of Occupational Medicine and Industrial Hygiene.

Humans↗

PubMed2004

[Influence of 100 Hz sinusoidal vibration on muscle spindle afferents of soleus muscles in suspended situation rat].

OBJECTIVE: To study influence of 100 Hz sinusoidal vibration on muscle spindle afferents discharges of rat soleus muscles in simulated-weightlessness situation. METHOD: The tail-suspended rat model was used to simulate weightlessness, and 100 Hz sinusoidal vibration was performed by a vibrator. Unit activity was recorded electrophysiologically from the centrally cut filaments of the spinal dorsal roots innervating muscle spindles of the rat soleus muscle; then observation on the changes in afferent discharges from muscle spindle in a rat soleus muscles were made after 7 d. RESULT: 1) Compared with control muscle spindle afferents discharges of rat soleus muscles decreased after 7 d tail-suspension (P<0.05). 2) Compared with suspension the afferent discharges from soleus muscle spindles increased after 7 d tail-suspension with 100 Hz sinusoidal vibration. CONCLUSION: Sinusoidal vibration (100 Hz; 300 micrometers) can selectively activate muscle spindles. Muscle spindle afferent input of the suspended rats increased after the application of 7 d 100 Hz sinusoidal vibration.

Afferent Pathways↗

PubMed2005

Acute effects of cold and muscle vibration on maximal grip strength and muscle endurance in normal subjects.

The objective of this study was to compare the acute effects of 10 minutes cold application and 50Hz, 90 seconds vibration of forearm muscles on maximum grip strength and muscle endurance in apparently healthy young adults. This within-subject factorial research study recruited eighty-nine subjects (49 males and 40 males) using a sample of convenience. Baseline maximum grip strength and endurance index were measured using a Jamar dynamometer. Cold and muscle vibration were applied within 48 hours interval to the forearm muscles of the subjects. Their grip strength and endurance index were measured; immediately, 5, and 10 minutes post-application of either stimuli. Data were analysed using independent t-test and one-way analysis of variance at 0.05 alpha. Results showed that neither vibration (P>0.05) nor cold (P>0.05) produced any significant effect on the maximum grip strength and the grip endurance at 5 and 10 minutes post application. The subjects however recorded significantly higher endurance index immediately post cold than they did immediately post vibration (P<0.05). We concluded that grip endurance was enhanced more by cold application than by muscle vibration. Cold rather than vibration may therefore be used to facilitate grip endurance during hand rehabilitation.

Acute Disease↗

PubMedDate not supplied

Health risks from occupational exposures to mechanical vibration.

Health effects of occupational exposure to hand-transmitted vibration (HTV) and whole-body vibration (WBV) are reviewed. Excessive exposure to HTV from powered processes or tools is associated with an increased occurrence of symptoms and signs of disorders in the vascular, neurological and musculoskeletal systems of the upper limbs. This complex set of disorders is called hand-arm vibration syndrome. Long-term occupational exposure to intense WBV is associated with an increased risk for disorders of the lumbar spine and the connected nervous system. With a lower probability, the neck-shoulder, the gastrointestinal system, the female reproductive organs, the peripheral veins, and the cochleo-vestibular system are also assumed to be affected by WBV. However, there is weak epidemiological support for WBV-induced disorders of organ systems other than the lower back. In addition to the health effects of human vibration, this review provides information on methods for the protection and health surveillance of vibration-exposed workers according to the European Directive 2002/44/EC on mechanical vibration.

Hand-Arm Vibration Syndrome↗

PubMed1991

[Analysis of the interference electromyogram of human soleus muscle after exposure to vibration].

The properties of m. soleus surface EMG recorded under conditions of voluntary contraction against vibrational stimulation were studied using vibration-triggered averaging and spectral estimates. The averaging procedure indicated EMG bursts locked to the vibration cycle. Narrow peaks appeared in the EMG spectrum at vibration frequency and harmonics. These effects were more pronounced in rectified EMG at low vibration frequencies (30-70 Hz) and in EMG at high frequencies (70-120 Hz). The disappearance of the peak after ischemic blockade preceded that of the tendon reflex. The peak normalized to the EMG power decreased when the force was enlarged. The peak augmented with prolonged contraction under vibration. The results are suggested to reflect alterations of the relative weight of the excitatory inflow through short spindle-motoneuron connections in the overall motoneuron inflow.

Adult↗

PubMed1989

Study on vibrations of the mandible.

In order to elucidate the phenomenon of vibrations of the mandible, a simplified plaster model was prepared and the fundamental vibrations were investigated. Studies using either dried human skulls or in situ mandible yielded similar results. The results obtained were as follows: 1. The vibrations generated by tapping a simplified mandible model were similar to those of the transverse type of a bar and tuning fork. 2. Both vibration models belonged to the transverse type bar vibrations. 3. Similar results were obtained by tapping the teeth of the mandible in situ. 4. The presence of fractures and cysts in the mandible might induce changes in vibrations.

Dental Stress Analysis↗

PubMed1989

Vibration stress and pharmacokinetics of rifampicin.

The influence of horizontal vibration stress on pharmacokinetics of rifampicin (RFP) 20 mg.kg-1 on rabbits was investigated. RFP was given orally or intravenously. The experiments were repeated one week later. The drug was administered immediately after 60 min of vibration like in control experiments on the same animals. Another group of animals was exposed to daily vibration for two weeks. The arrangement otherwise was the same as above. Serum levels of orally administered RFP were significantly decreased after a single vibration session. Repeated vibration exposure abolished the observed differences. The single vibration session had no effect on the pharmacokinetics of intravenously applied RFP.

Administration, Oral↗

PubMed1989

[Constitutional factors of resistance to the effects of local vibration].

The study directed at the improvement of vibration disease prevention shows that not only functional, but also constitutional and somatotypologic body characteristics should be taken into account in predicting resistance to the impact of local occupational vibration. Such approach is specified by the fact that the relation of the main body components affects the amount of the zone of tissues and organs involved into vibration process. The study of 300 assemblerriveters and metal workers engaged in mechanical assembly shows that workers with elevated content of fat tissue and relatively small amount of osteal and muscular tissue, i.e., representatives of the abdominal somatype, are most resistant to local vibration. When the content of osteal and muscular components increases and that of the fat one decreases (thoracic somatotype), resistance to local vibration experiences a significant decline. The dimensions of skin and fat folds of upper extremities are greatly correlated to local vibration resistance.

Anthropometry↗

PubMed1988

Protection against the lethal effects of whole body vibration by the alpha-adrenergic system in rat.

To investigate the protective mechanism against the lethal effect of whole body vibration, the phentolamine (1 mg/kg) pretreated rats were exposed to whole body vibration with a frequency of 20 Hz under an acceleration of 5 G at 24 +/- 2 degrees C and 5 +/- 1 degrees C. Five of 9 rats pretreated with phentolamine died from the exposure to whole body vibration within one hour at 24 +/- 2 degrees C. In these rats, marked infrapleural hemorrhage, dilatation of alveolar capillary vessels, and intraalveolar hemorrhage and edema were observed. However, all of the 10 rats pretreated with saline survived through the one hour exposure to the same vibration, and showed only slight histological changes in the lung. On the other hand, no rats pretreated with saline or phentolamine died from the exposure to whole body vibration within one hour at 5 +/- 1 degrees C. These results suggest that the alpha-adrenergic system and cold have a role of protection against the lethal effects of whole body vibration.

Animals↗

PubMedDate not supplied

[Effect of low-frequency whole-body vertical vibration on the serotoninergic system of the brain and spinal cord].

Rat experiments were performed to study variations in serotonin (5-HT) and its metabolite (5-hydroxy indole acetic acid) in different CNS compartments. Control animals were exposed to an acute vibration stress (10 Hz, 1 mm, 2 m/sec2, 15 min) and experimental animals to a prolonged (52-54 days) vibration test. Acute vibration led to 5-HT activation which was most significant in the hippocampus, diencephalon, cerebellum and in the sacrolumbar cord. Prolonged vibration caused an increase of 5-HT in the parietal cortex and its enhanced utilization in the striatum, diencephalon, pons and in the sacrolumbar cord. As compared to the controls, vibration produced a smaller accumulation of 5-HT in the hippocampus and a larger accumulation in the cerebellum, diencephalon, medulla oblongata and spinal cord. The paper discusses the role of regional changes in 5-HT metabolism and reactivity of serotoninergic structures in the mechanism of vibration-related somatosensory disorders.

Animals↗

PubMed1986

In vivo measurements of spinal column vibrations.

Recent epidemiological studies have indicated high risk factors for persons exposed to vibrations. We measured the in vivo responses of the lumbar vertebrae and sacrum of five volunteers who were subjected to pure sinusoidal vertical vibrations in the seated position. Two acceleration amplitudes were used, one and three meters per second squared, with frequencies ranging from two to fifteen hertz. Spinal vibration was measured for two lumbar vertebrae using a transducer that was attached directly to the spinous processes. Axial, horizontal, and rotatory accelerations in the sagittal plane were determined for each vertebra. Vertical acceleration at the sacrum was also measured. The amplitude ratios of the accelerations at the vertebrae and sacrum with respect to the acceleration of the seat were calculated. Our results show that the pure vertical sinusoidal input vibration at the seat produced vibrations of the lumbar vertebrae not only vertically but also horizontally, as well as a rotational vibration. The resonance frequency of the lumbar vertebrae in the vertical direction was an average of 4.4 hertz. Horizontal and rotatory resonance frequencies could not be determined.

Acceleration↗

PubMed1979

[Effect of vibration on the functioning of the lymphatic system in the small intestine in rat].

The production rate and flow of the lymph in mesenteric lymph vessels under normal conditions and after horizontal vibration of 5 Hz frequency and 20 mm amplitude were measured by means of intravital, intravenous injection of trypan blue water solution. The investigations were carried out on 66 Wistar rats of both sexes. It was found, that 3 and 7-hour vibration and everyday 7-hour vibration applied during a week result in the acceleration of lymph flow, whereas 3- and 4-week vibrations result in reduction of production and flow of the lymph. In all cases the lymph flow speed becomes normal after one day break. The results obtained show that low frequency vibration causes reversible functional changes in small intestine lymphatic system. These changes more probably result from hemodynamic disturbances. The applied vibration parameters did not cause any perceptible morphological changes in the lymphatic system.

Animals↗

PubMed1977

[Relations between working conditions and occurrence of vibration disease in forestry workers. I].

The level of mechanic vibrations intensity of 20 motor saws of the BK-3a type and 5 saws of the Partner R-11 type was determined and the evaluation of 460 motorsawers' vibration exposure--in case of working on these types of saws--was performed. The evaluation covered saws of various technical conditions, with which felling, cross-cutting and trimming of soft and hard timber were performed. The vibration measured exceeds 3--5 times Soviet hygienic normatives and ISO, especially in octave frequencies of 63 and 125 Hz. The intensity level of vibrations was significantly dependent on the technical conditions of the saw, activities performed with it and the hardness of timber. The evaluation of the woodcutters' exposure to vibration in a day, a year and the whole employment period was performed on the basis of the test-checking, the ammount of timber produced, fuel used for the saw and days of saw-work. Daily exposure to vibration was 2,4 +/- 1,2 hours and was of intermittent, irregular character. Motor-sawers worked with saws from 31 to 296 days a year, producing yearly from 973 to 10.503 m3 of timber as m3 of timber felled.

Humans↗

PubMed1977

[Correlation between work conditions and the occurrence of vibration disease in forestry workers II].

The frequency of occurrence of vibration disease in 460 randomly chosen sawworkers, from 20 to 65 years of age, working with motor-saws of the KBK-3a and Partner R-11 types was determined. The control group consisted of 136 forestry workers non-exposed to vibration. Vibration disease was observed in 22.6% of motor-sawers, and it was suspected in 6.7%. The occurrence of vibration disease is significantly dependent on the age, daily exposure to vibration, working period in years and--especially strongly--(p less than 0.001) on the amount of timber produced and fuel used for the saw. It was discovered that daily exposure to motor-saw vibration with the type BK-3a considered, should not exceed 2 hours a day. The amount of timber produced by the saw-worker as m3 of timber felled, should not exceed 5.000 m3 in a year and 40.000 m3 in the whole employment period.

Adult↗

PubMed1984

[A study on the thermographic diagnosis of vibration disease of tie-tamper operators in the Japanese National Railways].

There have been many studies of thermographic diagnosis of vibration disease, but few of them seem to have discussed tie-tamping machines as a cause. This study focuses on thermographic diagnosis of vibration disease in tie-tamper operators of the Japanese National Railways. In the diagnosis the subject's both hands were immersed in water at 10 degrees C for 3 minutes before being examined. Variables such as season, age, type of vibration tool used and total operating time were considered. These were selected as outside variables and thermographic results as dependent variables, in Quantification Method II. Season and confirmation of vibration disease were found to have a relationship to thermographic scaling, but no such relationship was found for age, type of vibration tool used, or total operating time. A cross-analysis of variables confirmed the relationship with season, and revealed that there were fewer confirmed cases of vibration disease in spring and summer than in fall and winter. It was finally concluded that thermographic analysis is more reliable in colder weather.

Adult↗

PubMed1982

[Studies on the vibration disease - an attempt of a new classification (author's transl)].

In the first section of this study, a survey was made of 1,215 subjects who had been using mowing madchines. Of them 548 subjects without clinical symptomes were examined closely. Vibration threshold and maximal grasping power showed a normal distribution. Since the values decreased with an advancing age, limit values for each age range were calculated from respective probability vales. Advancing age did not affect skin temperature which showed a skewed distribution: limit values therefore were obtained from cumulative frequency distribution. In the second section, we investigated the actual conditions of the authorized patients with vibration diseases. Few severe cases were encountered, but adequacy of the conventional classification as to the degree of severity was questioned. Finally, an attempt was made to classify the disorder according to our new criteria of RNA system. The new system revealed that the vibration disease is classifiable into 7 types: R, N, A, RN, RA, NA and RNA. Single form such as R and N type appeared relatively earlier in life with shorter duration of exposure to vibrating machines. A few cases of A type were seen. Combination form such as RN, RA, NA and RNA type was the form of more severly deranged disorder, as judged from the age of onset, duration of exposure to vibrating machines, physical signs and also laboratory findings.Therefore, the new classification with RNA system appears more adequate in describing the pathosymptomatology of the vibration disease than the conventional method hitherto used.

Adult↗

PubMed1984

[Effect of pure sound and vibration on the embryonic development of the mouse].

Studies were conducted about the effects of noise and vibration on the ontogenesis of mouse. Application of noise and vibration was carried out in 340 female mice in the phenocritical phase. The parameters of pure sound were 100 dB and 10.000 Hz. The vibration was carried out with the oscillating velocity of 87,1 mm/s and the oscillating acceleration of 3,45 X 10(4) mm/s2. The duration of noise was 10 hours, of vibration 4 and 8 hours. In an other experiment the animals were exposed to the combination of noise (10 h) and vibration (4 h). 581 fetuses were evaluated by subsequent parameters: Fetal length and weight, placental diameter, resorptions and haematomas. It was concluded that retardations, resorptions and haematomas were results from noise and vibration exposure. A teratogenic effect of these noxes was not evident. Probable the noxes evoked stress reactions in the female animals. Subsequently a constriction of blood vessels impairs the placental function.

Animals↗

PubMed1978

Intensity judgements of non-sinusoidal vibrations; support for the ISO weighting method.

Three experiments were conducted to compare the independent component method and the weighting method, recommended by current vibration standards for evaluating complex vibrations. Seated subjects matched their perceptions of the intensity of various Z-axis vibrations by adjusting the intensity of a sinusoidal matching frequency. Exp. I stimuli were composed of from one to four sinusoids in the frequency range from 11--63 Hz, Exp. II stimuli were made up of from one to four third-octave bands of random vibration with center frequencies from 16--40 Hz, and Exp. III stimuli were composed of from one to four sinusoids from 2.6--16 Hz. In all three experiments, the acceleration of the matching response increased significantly as the number of sinusoids or third-octave bands in the stimulus increased. Such a relationship is not predicted by the independent component method, but is predicted by the weighting method. Moreover, when the weighted accelerations of the matching responses are compared with the weighted accelerations of the input vibrations, the correspondence is quite good for all three experiments. These results support adoption of the weighting method as the preferred procedure for evaluating complex vibration environments.

Acceleration↗